Potential successors: Three possible replacements for Jon Kyl.

The prospect of Jon Kyl resigning from the U.S. Senate has reignited speculation of who Gov. Doug Ducey might consider to finish the term for the seat held for 30 years by the late Sen. John McCain.

Ducey has said he hopes Kyl, an Arizona Republican, serves in the Senate until the 2020 election when the seat would appear on the ballot. But if Kyl bows out earlier, Ducey must appoint another Republican.

The governor and some of his closest aides refuse to discuss any private deliberations that likely are taking place.

The governor’s thinking on a potential second appointment is unknown, so it is unclear how he may weigh pressure from power players in the White House and on Capitol Hill against advice by friends, staffers and donors in Arizona.

Here are three names that are being discussed as potential appointees:

Martha McSally

The two-term congresswoman who represents a Tucson-area district just lost her bid for the state’s other Senate seat to Democrat Kyrsten Sinema.

Her loss handed Democrats their first Senate win in 30 years, but her showing may provide the governor with a measure of confidence that she could win again if given another shot.

Senate Majority Leader Mitch McConnell, RKentucky, supported McSally and important Republican donors spent millions of dollars on her election effort and likely want to see that investment pay off. Ducey and McSally share some of the same deep-pocketed donor base.

McSally’s biography as the nation’s first female combat pilot is compelling.

But McSally tethered herself throughout the 2018 election cycle to President Donald Trump and a national hard-right playbook instead of one that reflected the state’s more nuanced electoral landscape. Her Missouribased campaign consultants blamed her loss, on media coverage, Trump’s favorability, outspending by Sinema and her allies, and Sinema’s lack of a competitive primary, among other factors. The campaign did not take ownership of the loss, according to a post-campaign memo, obtained by The Washington Post.

Kirk Adams

One of Ducey’s most trusted advisers, the former speaker of the Arizona House of Representatives has been the governor’s wingman for the past four years.

As Ducey’s chief of staff, Adams was at the table and on sensitive phone calls with legislative leadership on issues ranging from tax policy to health-care reform. And he was Ducey’s point man on strengthening Arizona’s relationship politically and economically with Mexican officials on the border and in Mexico City following Gov. Jan Brewer’s administration.

After Ducey won reelection, Adams announced he was stepping down. His last day is on Dec. 14. Adams would not discuss his future plans in detail.

Adams has close relationships with influential Republican donors who may be willing to heavily invest in someone who shares many of the same policy ideals.

An Adams appointment was once viewed as potentially risky for Ducey, but his name has been back in circulation since McSally’s loss.

Eileen Klein

The state treasurer and former chief of staff to Brewer, Klein has deep experience in state government and Arizona politics.

The governor appointed her as state treasurer last April after Republican Jeff DeWit accepted a job with Trump’s administration.

She served on Ducey’s transition team in 2014 after his first gubernatorial win. Before he appointed her as treasurer, Klein was president of the Arizona Board of Regents, which governs the state’s universities.